Basic Research On The Phase Separation Behavior And Its Inhibition Of Asphaltene

The phase separation behavior of asphaltene brings about many problems to production, processing and transportation of petroleum. Because of the complexity of aspaltene structure, its physical and chemical properties etc., these problems haven't been solved effectively. Therefore, a convenient method of detecting the phase separation behavior of asphaltene and inhibiting it need to be established.In this paper, American viscous oil, Liao-he viscous oil, Ta he crude oil were the study objects. The effects of structure of asphaltene, feed composition, reaction conditions et al on phase separation behavior of asphaltene were studied firstly. The results showed that the asphaltene with bigger molecular weight, lower H/C atomic ratio, larger aromatic ring numbers (RA) was easier to associate and lead to the phase separation in asphaltene-toluene solution; the phase separation behavior of asphaltene had something to do not only with the amount of the asphaltene, but also with the amount of resin and their similarity. With the increase of concentration of asphaltene solution, the phase separation was easier to occur. With the increase of the amount of resin and their similarity, the phase separation was more difficult to occur; the bigger was the molecular weight of the precipitant, the more difficult for the phase separation behavior of asphaltene to occur, the smaller is the weight of the precipitation; the high temperature and long time during the thermal reaction could promote the phase separation behavior of asphaltene and increase the coke yield.The law of phase separation behavior of asphaltene was applied to study the preparation of synthetic petroleum, the mechanism of viscosity reducer and inhibiting the coking of petroleum. The results showed that the higher was the recycle ratio, the smaller was the amount of coking liquid product needed to prepare the synthetic petroleum. The viscosity of the synthetic petroleum was 380mm2/s at 50oC. The viscosity of the synthetic petroleum increased with the prolonging of the storage time.The possible mechanism of viscosity reducer was: the molecule of viscosity reducer with strong ability to form hydrogen bond infiltrated and dispersed into the molecules of asphaltene and resin, broke up the aggregate partly, the number of asphaltene and resin in the aggregate decreased, the cohesive force of petroleum reduced, then the viscosity of the synthetic petroleum decreased.The coking can be inhibited when the distillate selected was compatible with residue. The coke induction period increased with the ratio of the fraction oil mixed; the coke induction period shortened with the reaction temperature increased; the higher was the reaction temperature, the smaller was the effect of temperature on the coke induction period. In addition, some polycyclic aromatic compounds which can release active hydrogen can be used as coking inhibitor.